A Knight in Waiting — Juliet Landon

Lady Aletta Markenfield relished the freedom of widowhood. It was a grief to her that she had proven to be barren, but otherwise she could not regret the death of her brutal husband. The arrival of new neighbor Sir Geraunt de Paine overturned all her pleasure - the laxity in the wake of the Black Death meant that some of Sir Geraunt's serfs had moved to her estate, and Geraunt had no hesitation about using blackmail! Aletta was faced with equally upsetting choices -- disrupt the fledgling families or become Geraunt's mistress. Disguising the fact with a betrothal ring was small comfort. Though Sir Geraunt threatened to use her secrets against her unless she became his mistress, Lady Aletta found herself strangely exhilarated by his presence. What's more, she was about to discover that he had a secret of his own.